Synthesis, Structural Regulation And Properties Of The Pillar[5]arene Coordination Polymers

As a new class of macrocyclic host molecule, pillararene has received much attention in the past few years due to its unique structure and potential applications in molecular recognition, fluorescence sensing and the controllable release of drug et al. Herein, one pillar[5]arene molecule containing ten carboxyl groups was synthesized and used as organic ligand. Based on coordination and supramolecular chemistry, a series of cadmium and copper coordination polymers with novel structures and unique functions were prepared from pillar[5]arene ligand. These coordination polymers were characterized by a variety of techniques, such as elemental analysis, IR spectrum, and powder and single crystal X-ray diffraction and so on. Additionally, we also investigate their properties in fluorescence, molecular recognition, biosensors and so on. This thesis includes the following four chapters.In chapter 1, the recent development of pillar[5]arene and its derivatives was summarized, including their synthesis, molecular recognition, supramolecular assembly and application. An overview of the thesis topic was also presented.In chapter 2, the pillar[5]arene ligand containing ten carboxyl groups was synthesized in four steps from 1,4-dimethoxybenzene and paraformaldehyde. Using solvothermal method, three coordination polymers 1-3 with distinct structures were synthesized by reacting ligand HL and Cd²⁺ ion. X-ray structural analysis shows that polymers 1-3 feature three kinds of supramolecular networks?three-dimensional network structure, three-dimensional wave-like structure and three-dimensional columnar structure?, Additionally, the three Cd?II? complexes exhibit disparate photophysical properties due to their different structures. Finally, the fluorescence response behavior of the coordination polymer 2 was investigated by the titration of different sugar molecules. The the quenching efficiency of maltose molecule was the best in comparison with other sugar molecules.In chapter 3, using 4,4-dipyridyl and acridine as starting materials, three guest molecules with positive charge were synthesized in one step reaction. Adding different guest molecules?methyl viologen, butyl viologen and acridinium salt? and solvent molecule into the reaction system of ligand HL and Cd?II? ions, four pillar[5]arene coordination polymers 4-7 were prepared. X-ray diffraction analysis indicates that the guest molecules and the solvent molecules can effectively induce the structural diversification of metal-pillar[5]arene framework. This change can be attributed to the coordination ability of the solvent molecules, the size and shape of guest molecules, and the different alkan chains in the guest molecules.In chapter 4, using solvothermal method, one novel metal-organic framework?P5ACu? with unique three-dimensional channels was obtained by reacting pillar[5]arene ligand HL with Cu²⁺ ion. A single-crystal X-ray diffraction study reveals that the carboxyl groups of pillar[5]arene ligands in P5 ACu were linked into channels by coordinating with Cu²⁺ ions. In addition, its biosensing properties was also investigated. Firstly, P5 ACu was modified on the surface of glassy carbon electrode?GCE? by electrochemical deposition method, then the P5ACu/GCE modified electrode was used to electrochemical detection of dopamine?DA? by cyclic voltammetry method; The differential-pulse voltammetry?DPV? method was used in order to detect the different concentration of DA in the buffer solution. The results show that the certain detection limit is 3 mM, and the detection range is 5-190 mM. The modified electrode P5A_Cu/GCE has good repeat ability and immunity.